import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { Type } from "typebox";
import { StringEnum } from "@earendil-works/pi-ai";
import type MemoryClient from "mem0ai";
import type { Scope, ScopeContext, Mem0Config } from "../types.ts";
import { DEFAULT_CUSTOM_CATEGORIES } from "../types.ts";
import { resolveSearchFilters, resolveAddParams } from "./scoping.ts";
import { formatMemoryList } from "./formatting.ts";
import { captureToolEvent } from "../telemetry.ts";

interface MemoryResult {
  message?: string;
  eventId?: string;
  status?: string;
}

const MAX_OUTPUT_LINES = 200;
const MAX_OUTPUT_BYTES = 50_000;

function truncateOutput(text: string): string {
  const lines = text.split("\n");
  if (lines.length <= MAX_OUTPUT_LINES && text.length <= MAX_OUTPUT_BYTES) {
    return text;
  }

  const kept = lines.slice(0, MAX_OUTPUT_LINES);
  let result = kept.join("\n");
  if (result.length > MAX_OUTPUT_BYTES) {
    result = result.slice(0, MAX_OUTPUT_BYTES);
  }

  const dropped = lines.length - kept.length;
  if (dropped > 0 || text.length > MAX_OUTPUT_BYTES) {
    result += `\n\n[Output truncated: showing ${kept.length} of ${lines.length} lines]`;
  }
  return result;
}

interface ToolParams {
  action: "search" | "add" | "get_all" | "update" | "delete" | "delete_all";
  query?: string;
  content?: string;
  memory_id?: string;
  scope?: Scope;
}

export function buildToolExecute(
  mem0: MemoryClient,
  scopeCtx: ScopeContext,
  defaultScope: Scope,
) {
  return async (params: ToolParams, signal?: AbortSignal) => {
    const scope = params.scope ?? defaultScope;

    switch (params.action) {
      case "search": {
        if (signal?.aborted) throw new Error("Cancelled");
        if (!params.query) throw new Error("query is required for search");
        const filters = resolveSearchFilters(scope, scopeCtx);
        const result = await mem0.search(params.query, { filters });
        const memories = result.results ?? [];
        return {
          content: [{ type: "text" as const, text: truncateOutput(formatMemoryList(memories)) }],
          details: { matchCount: memories.length },
        };
      }

      case "add": {
        if (signal?.aborted) throw new Error("Cancelled");
        if (!params.content) throw new Error("content is required for add");
        const addParams = resolveAddParams(scope, scopeCtx);
        const result = await mem0.add(
          [{ role: "user", content: params.content }],
          { ...addParams, customCategories: DEFAULT_CUSTOM_CATEGORIES },
        );
        const res = result as MemoryResult;
        const msg = res.message ?? "Memory stored.";
        return {
          content: [{ type: "text" as const, text: msg }],
          details: { eventId: res.eventId ?? null, status: res.status ?? null },
        };
      }

      case "get_all": {
        if (signal?.aborted) throw new Error("Cancelled");
        const filters = resolveSearchFilters(scope, scopeCtx);
        const result = await mem0.getAll({ filters });
        const memories = result.results ?? [];
        return {
          content: [{ type: "text" as const, text: truncateOutput(formatMemoryList(memories)) }],
          details: { totalCount: result.count ?? memories.length },
        };
      }

      case "update": {
        if (signal?.aborted) throw new Error("Cancelled");
        if (!params.memory_id) throw new Error("memory_id is required for update");
        if (!params.content) throw new Error("content is required for update");
        const updateResult = await mem0.update(params.memory_id, { text: params.content });
        const res = updateResult as MemoryResult;
        return {
          content: [{ type: "text" as const, text: res.status ?? "Memory updated." }],
          details: { memoryId: params.memory_id },
        };
      }

      case "delete": {
        if (signal?.aborted) throw new Error("Cancelled");
        if (!params.memory_id) throw new Error("memory_id is required for delete");
        const result = await mem0.delete(params.memory_id);
        return {
          content: [{ type: "text" as const, text: result.message ?? "Memory deleted." }],
          details: {},
        };
      }

      case "delete_all": {
        if (signal?.aborted) throw new Error("Cancelled");
        const delParams = resolveAddParams(scope, scopeCtx);
        const result = await mem0.deleteAll(delParams);
        return {
          content: [{ type: "text" as const, text: result.message ?? "All memories deleted." }],
          details: {},
        };
      }
    }
  };
}

export function registerMemoryTool(
  pi: ExtensionAPI,
  mem0: MemoryClient,
  config: Mem0Config,
  getScopeCtx: () => ScopeContext,
  telemetryCtx?: { apiKey?: string },
): void {
  pi.registerTool({
    name: "mem0_memory",
    label: "Mem0 Memory",
    description:
      "Search, add, update, and manage persistent semantic memories powered by Mem0. Memories persist across sessions and devices. Use action \"search\" proactively -- before answering anything that may depend on what the user told you earlier -- and run multiple searches with different phrasings for multi-part questions. Output is truncated to 200 lines / 50KB.",
    promptSnippet: "Semantic memory search and storage via Mem0",
    promptGuidelines: [
      'Use mem0_memory with action "search" proactively whenever the request may depend on the user\'s past work, preferences, decisions, or environment -- not only when they explicitly mention the past',
      'For multi-part or comparative questions, run several searches with different phrasings and combine the results before answering -- one search is rarely enough',
      'Use mem0_memory with action "add" to save important facts, preferences, goals, decisions, or lessons the user shares',
      'Use mem0_memory with action "update" to modify an existing memory — requires memory_id and content. Preserves the memory ID',
      "Always use the default project scope unless the user EXPLICITLY asks to search across all projects — only then use scope \"global\"",
      "Do NOT pass scope at all for normal queries — omitting it uses the project default automatically",
    ],
    parameters: Type.Object({
      action: StringEnum(
        [
          "search",
          "add",
          "get_all",
          "update",
          "delete",
          "delete_all",
        ] as const,
        {
          description:
            "Memory operation to run: \"search\" (semantic recall -- use proactively before answering; run several with different phrasings for multi-part questions), \"add\" (save a new fact/preference/decision), \"get_all\" (list everything in scope, no query needed), \"update\" (replace an existing memory's text by id), \"delete\" (remove one memory by id), \"delete_all\" (wipe every memory in the scope -- destructive, only on explicit request).",
        },
      ),
      query: Type.Optional(
        Type.String({
          description:
            "Search text -- required for action \"search\". Use a focused noun-phrase; for multi-part questions run several searches with different phrasings.",
        }),
      ),
      content: Type.Optional(
        Type.String({
          description:
            "Memory text -- required for action \"add\" (the fact to store) and \"update\" (the replacement text).",
        }),
      ),
      memory_id: Type.Optional(
        Type.String({
          description:
            "Target memory's ID -- required for \"update\" and \"delete\". Use an ID returned by a prior \"search\" or \"get_all\".",
        }),
      ),
      scope: Type.Optional(
        StringEnum(["project", "session", "global"] as const, {
          description:
            "Where to read/write: \"project\" (default -- this repo), \"session\" (this run only), or \"global\" (across ALL projects; only when the user explicitly wants cross-project recall). Omit for normal queries.",
        }),
      ),
    }),
    async execute(toolCallId, params, signal, onUpdate, ctx) {
      const scopeCtx = getScopeCtx();
      const exec = buildToolExecute(mem0, scopeCtx, config.defaultScope);
      const start = Date.now();
      try {
        const result = await exec(params as ToolParams, signal);
        const details = (result as any).details ?? {};
        captureToolEvent((params as ToolParams).action, {
          success: true,
          latency_ms: Date.now() - start,
          result_count: details.matchCount ?? details.totalCount ?? undefined,
        }, telemetryCtx);
        return result;
      } catch (err) {
        captureToolEvent((params as ToolParams).action, {
          success: false,
          latency_ms: Date.now() - start,
          error_type: err instanceof Error ? err.name : "unknown",
        }, telemetryCtx);
        throw err;
      }
    },
  });
}